Civometry calculation
Change in the share of usual residents by religion, Census 2011 to Census 2021
Usual residents in each religion category as a share of all usual residents at Census 2021 (ONS TS030) minus the same share at Census 2011 (ONS KS209), in percentage points.
How it is calculated
- Numerator
- Census 2021 religion · split by Religion
- Denominator
- Census 2021 usual residents
- Formula
- the later share minus the earlier share, in percentage points
- Result is measured in
- percentage points
- Which population is used
- same period
- Suppressed when
- the numerator is below 10 or the population below 1,000, so small numbers are not published as rates
How the categories are matched
The two sources do not use the same category names. Every numerator category is mapped to exactly one denominator category, and nothing is merged or dropped silently.
| In the numerator | Matched to |
|---|---|
| Christian | Christian |
| Muslim | Muslim |
| Hindu | Hindu |
| Sikh | Sikh |
| Jewish | Jewish |
| Buddhist | Buddhist |
| Other religion | Other religion |
| No religion | No religion |
| Not answered | Not answered |
What it covers
Geographies present at both censuses under the same code; areas whose code changed between 2011 and 2021 are not computed until the geography stream's lookup lands.
What this calculation cannot tell you
- A change in share is in percentage points, never a percentage increase; a group moving from 4.8 per cent to 6.5 per cent rose 1.7 points, not 35 per cent (that figure is the pct_change of the count, a separate measure).
- The religion question is voluntary; "Not answered" is a category in both censuses and is included in the denominator.
- Shares at both censuses are of all usual residents at that census, so population growth changes the denominator between the two dates.
Check it yourself
Every calculated value stores the numerator, the denominator and the identifiers of the two official observations it came from. Open the numerator and denominator above, take the figures for the same period and category, and apply the formula. If you get a different answer, tell us where it diverges.